21 June 2012

The Vocabulary of Self-Reliance: EMP, HEMP, and CME

EMP: An ElectroMagnetic Pulse (EMP) is a high-intensity burst of electromagnetic energy caused by the rapid acceleration of charged particles.This abrupt pulse of electromagnetic radiation usually results from a nuclear explosion, or from a suddenly fluctuating magnetic field. The resulting rapidly-changing electric fields and magnetic fields may interact with electrical/electronic systems to produce current and voltage surges that can damage or destroy unprotected electronic devices. An EMP attack on the United States could irreparably cripple the country by shutting down power grids, sources, and supply mechanisms.

HEMP: In military terminology, a nuclear warhead detonated hundreds of kilometers above the Earth's surface is known as a High-altitude ElectroMagnetic Pulse (HEMP) device. Effects of a HEMP device depend on a very large number of factors, including the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth's magnetic field, and electromagnetic shielding of targets. Generally speaking, most people who are concerned about an EMP attack are really concerned with a HEMP event.

CME: A Coronal Mass Ejection (CME) is a large cloud of plasma and magnetic fields that erupts from the Sun. A CME can erupt from the sun in any direction, but only when the cloud is aimed at Earth will it potentially have any effect. As the CME moves through the interplanetary medium (the plasma-like material that fills the solar system), it can create a disturbance known as a geomagnetic storm. These geomagnetic storms can disrupt communications or navigation systems, but the more damaging (and most frightening) effect that can be produced is damage to the electrical power grid. The geomagnetic storm can induce electrical currents in long power grid transmission lines, which can damage transformers across a very wide area, which can also lead to a cascading power failure.

For more information on the above, visit our EMP/CME category of posts here on this blog. If you'd like to read more about what life might be like after an EMP attack or a CME event, check our William R. Forstchen's EMP 101 page. Forstchen is the author of One Second After, which is a well-researched novelization of life in Black Mountain, North Carolina after an EMP attack on America.

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